The present invention provides a useful tool for performing the method for producing compound thin films presented in U.S. Pat. No. 4,058,430. According to that method, referred to as ALE (Atomic Layer Epitaxy), high quality compound thin films can be produced by subjecting the surface to be grown to successive reactive vapors which make the surface grow by a single atomic layer in each reaction step.
When compared to thin film deposition concepts of the prior art, the ALE demand for separated surface reactions of different reactive vapors gives rise to special requirements for the equipment and method of performing the ALE growth. In U.S. Pat. No. 4,058,430 these requirements were approached using classical vacuum deposition techniques by providing separate reaction regions or periods, separated from each other by a region or period of high vacuum condition. Due to leaks of the reactive vapors from the reaction regions, and due to residual vapors especially in the case of exchange surface reactions, difficulties are found in obtaining the high vacuum condition needed for the successful separation of the reaction steps. These problems take away from an advantage of the ALE invention, wherein the self-stabilizing growth rate property of the ALE-method is obtained by using quantities of reactive vapors which contain reactive atoms in excess to the amount needed for a full surface coverage in a single surface reaction step.